The Division of Pediatric Hematology and Oncology at UCLA-Harbor General Hospital was elected to full membership in Children's Cancer Study Group A in June 1972 and became funded by the NCI on June 1, 1973. The purpose of this proposal is to continue to develop and increase the participation of the unit at Harbor General Hospital and affiliated institutions in all phases of the national cooperative program of clinical cancer investigation of children. Investigators associated with this program are located in the major referral centers for a population of 3.3 million people. The purpose of the Children's Cancer Study Group A is to design and coordinate clinical investigations in various neoplastic disorders of children.